<!DOCTYPE html>
<html lang="zh-CN">
	<head>
		<meta charset="UTF-8" />
		<meta http-equiv="X-UA-Compatible" content="IE=edge" />
		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
		<title>1_引出生命周期</title>
	</head>
	<body>
		<!-- 准备好一个“容器” -->
		<div id="test"></div>

		<!-- 引入react核心库 -->
		<script type="text/javascript" src="../js/react.development.js"></script>
		<!-- 引入react-dom，用于支持react操作DOM -->
		<script type="text/javascript" src="../js/react-dom.development.js"></script>
		<!-- 引入babel，用于将jsx转为js -->
		<script type="text/javascript" src="../js/babel.min.js"></script>
		<script type="text/babel">
			// 创建组件
			// 生命周期回调函数 <=> 生命周期钩子函数 <=> 生命周期函数 <=> 生命周期钩子
			class Life extends React.Component {
				state = { opacity: 1 };

				death = () => {
					// 卸载组件
					ReactDOM.unmountComponentAtNode(document.getElementById("test"));
				};

				// 组件挂在完毕时  组件挂载页面之后调用
				componentDidMount() {
					console.log("componentDidMount");
					this.timer = setInterval(() => {
						// 获取原状态
						let { opacity } = this.state;
						// opacity 减少0.1
						opacity -= 0.1;
						if (opacity <= 0) {
							opacity = 1;
						}
						this.setState({ opacity });
					}, 200);
				}

				// 组件将要卸载
				componentWillUnmount() {
					console.log("componentWillUnmount");
					// 清除定时器
					clearInterval(this.timer);
				}

				// render调用的时机：初始化渲染，状态更新之后
				render() {
					console.log("render");
					return (
						<div>
							<h2 style={{ opacity: this.state.opacity }}>React学不会怎么办</h2>
							<button onClick={this.death}>不活了</button>
						</div>
					);
				}
			}
			// 渲染组件
			ReactDOM.render(<Life />, document.getElementById("test"));
		</script>
	</body>
</html>
